Weigh or measure the light brown, dark brown, and white sugar into a bowl. In another bowl, weigh or measure the flour, oats, salt, baking soda, and baking powder, running a whisk through to blend.
Using a stand or hand-held mixer, cream the butter for a minute or two, then add the sugars and mix on a medium mixer speed for 2 to 3 minutes. Turn off the mixer and scrape down the side, then add the vanilla extract before turning the mixer back on to medium speed. I take one of the eggs, crack it into a small bowl to ensure there are no eggshells, and add it to the cookie batter. Mix into the cookie dough before adding the 2nd egg.
I scrape down the sides to ensure all the egg has been incorporated and turn the mixer to a low speed before adding the flour mixture. After all the flour mixture has been added, I scrape the sides down, add the chocolate chips, and mix them evenly throughout the cookie dough.
Preheat the oven to 350°F (175°C or 180°C). Take a 9X13 baking dish and lightly spray with Pam if not using a non-stick pan. To assemble, divide the cookie dough in half. I took tablespoons of cookie dough and dropped them around the bottom of the baking pan. Flour your hands and lightly dust the mounds of cookie dough with the flour. As you start to work and spread the cookie dough to cover the dish's bottom, you can dust the cookie dough with more flour if needed.
Once the cookie dough is pressed down and covering the bottom of the baking dish, take the cranberries and sprinkle them around evenly. Next, take the cinnamon chips and sprinkle them around. Using the other half of the cookie dough, I take a teaspoon and put little mounds on top of the cranberries and cinnamon for the top. Spread the mounds to loosely cover the filling using the back of the spoon or your floured fingers. When it bakes, the top cookie dough does spread and fills in small gaps. Bake for 23-26 minutes until the top is medium golden brown.
You will want to let the dish cool completely before cutting it into squares; this helps keep all the layers together. I let mine cool for at least 2 hours, sitting on two trivets to cool the bottom. If you are in a hurry, you can put the pan in the refrigerator to cool faster.